The disclosed technology relates to non-basic ashless compounds having sufficient polarity to act as dispersants. The disclosed technology additionally relates to the use of the ashless compounds in engine lubricants as dispersants for preventing engine deposits without degrading seals or increasing (i.e. contributing to) corrosion of yellow metals.
Detergent or dispersant compounds, depending on the compound's constitution, may upon combustion yield a non-volatile material such as, for example, boric oxide or phosphorus pentoxide. However, ashless detergents and dispersants do not ordinarily contain metal and therefore do not yield a metal-containing ash on combustion. Many types of ashless dispersants are known in the art.
(1) “Carboxylic dispersants” are reaction products of carboxylic acylating agents (acids, anhydrides, esters, etc.) reacted with nitrogen containing compounds (such as amines), organic hydroxy compounds (such as aliphatic compounds including monohydric and polyhydric alcohols, or aromatic compounds including phenols and naphthols and aromatic amines), and/or basic inorganic materials. These reaction products include imide, amide, and ester reaction products of carboxylic ester dispersants. Examples of these “carboxylic dispersants” are described in British Patent 1,306,529 and in many U.S. Patents including the following: U.S. Pat. Nos. 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, and Re. 26,433.
(2) “Amine dispersants” are reaction products of relatively high molecular weight aliphatic halides and amines, preferably polyalkylene polyamines. Examples thereof are described, for example, in the following U.S. Pat. Nos. 3,275,554, 3,438,757, 3,454,555, and U.S. Pat. No. 3,565,804.
(3) “Mannich dispersants” are the reaction products of alkyl phenols with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). The materials described in the following U.S. Patents are illustrative: U.S. Pat. Nos. 3,036,003, 3,236,770, 3,414,347, 3,448,047, 3,461,172, 3,539,633, 3,586,629, 3,591,598, 3,634,515, 3,725,480, 3,726,882, and U.S. Pat. No. 3,980,569.
(4) Post-treated dispersants are obtained by reacting a carboxylic, amine or Mannich dispersant with reagents such as dimercaptothiadiazoles, urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, phosphorus compounds or the like. Exemplary materials of this kind are described in the following U.S. Pat. Nos. 3,200,107, 3,282,955, 3,367,943, 3,513,093, 3,639,242, 3,649,659, 3,442,808, 3,455,832, 3,579,450, 3,600,372, 3,702,757, and 3,708,422.
(5) Polymeric dispersants are interpolymers of oil-solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar substituents, e.g., aminoalkyl acrylates or acrylamides and poly-(oxyethylene)-substituted acrylates. Examples of polymeric dispersants thereof are disclosed in the following U.S. Pat. Nos. 3,329,658, 3,449,250, 3,519,656, 3,666,730, 3,687,849, and 3,702,300.
The above-noted patents are incorporated by reference herein for their disclosures of ashless dispersants.
Ashless dispersants are important additives in engine lubricants for various purposes. One function of dispersants in engine lubricants is to maintain solid particles in suspension, thereby controlling undesirable engine deposits. However, the higher the treat rate of a dispersant in an engine oil, the more likely the dispersant will cause degradation of engine seals and corrosion. Thus, there is a need for an ashless compound that provides sufficient polarity to act as a dispersant, but does not induce seal degradation or corrosion.